<!DOCTYPE html>
<html lang="zh">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>DOM 1</title>
  <style>
    .red-{
      background: red;
    }
    .blue{
      background: blue;
    }
  </style>
</head>
<body>
  <div>
    <div id="test">test <span class="red">test1</span><span class="red-">test2</span></div>
    <div id="test2"><p class="red">段落标签3</p> </div>

  </div>
  示例
  <div id="empty">
    <div id="e1"></div>
    <div id="e2"></div>
    <div id="e3"></div>
  </div>
  <div id="siblings">
    <div id="s1"></div>
    <div id="s2"></div>
    <div id="s3"></div>
  </div>
  <div id="travel">
    <div id="t1">t1</div>
    <div id="t2">t2</div>
    <div id="t3">t3</div>
  </div>
  <script src="./dom.js"></script>
  <script src="./main.js"></script>
</body>
</html>